Urban and suburban environments that encourage physical activity have great potential to prevent a variety of diseases, especially cardiovascular disease. Recent studies suggest that land use and street design strongly influence whether people choose to travel by foot or bicycle. Because walking and bicycling can significantly promote health, we propose to carefully investigate the relationship between land use and street design, and walking and bicycling. We propose to link data on land use, mainly from the US Census, with data on walking and bicycling from detailed surveys of the US Department of Transportation. Specifically, we will address to what extent the following aspects of land use are associated with walking and bicycling: street patterns; proximity of potential employers; relative diversity of socio-economic groups; proximity of destinations for personal and recreational activities; and density of the resident population. The proposed research will be among the first to identify specific features of land use that are most consistently associated with walking and bicycling. The study is intended to promote general and cardiovascular health by contributing to policy decisions concerning urban and suburban development and design.